This invention relates to a intake valve structure for an internal combustion engine and more particularly to an improved valve placement arrangement and valve actuating mechanism.
It is well known that the specific output of an internal combustion engine can be increased by using plural valves for each combustion chamber. For this reason, the use of four valves per cylinder is widely becoming adopted, particularly in high performance engines. Still further increases can be enjoyed by utilizing more than four valves per cylinder. However, there is a practical limit to the number of valves that can be used in a given cylinder which is determined by the valve placement, valve actuating mechanism and combustion chamber configuration. With conventional valve placement, the increased number of valves gives rise to a combustion chamber configuration that prevents an undesirably high surface area and which also increases the clearance volume so that high compression ratios are not possible. As a result, the previously proposed valve placements have practically limited the number of valves per cylinder to four.
It is, therefore, a principal object of this invention to provide an improved valve placement arrangement for an internal combustion engine that permits the use of more than four valves per cylinder.
It is another object of this invention to provide a valve placement system for an internal combustion engine that permits high compression ratios and small combustion chamber surface areas.
In addition to the geometric configurations discussed above, the use of plural valves for a single combustion chamber also can give rise to problems in connection with spark plug placement and accessibility. If four or more valves are used for a given combustion chamber, it has been difficult with previously proposed arrangements to operate all of the valves from a single camshaft and still permit the use of a single centrally positioned spark plug. As a result, it has been necessary to resort to the use of two or more camshafts for operating the valves and this gives rise to complexity of the engine and increased cost.
It is, therefore, a still further object of this invention to provide an improved valve actuating mechanism for an internal combustion engine that will permit a central spark plug placement and which will permit the use of only a single camshaft for operating all valves.